Various forms of perpetual calendars heretofore have been provided, but many are confusing to those persons who find it difficult to remember the number of days which occur in each specific month. Perpetual calendars usually include a viewing window or area through which 42 day spaces may be viewed and a portion of the calendar disposed behind the viewing window has 57 month day indicia thereon arranged in seriatim repetitively in coordinates of seven and the aforementioned calendar portion is shiftable relative to the window in order that the desired total number of month days may be registered with the viewing window. The shiftable calendar portion must be adjusted to a particular position for each month in order that the first day of the month may start on the correct day of the week and after once being correctly adjusted, the day numbers of that month each are correctly positioned according to the days of the week. However, inasmuch as some months have 28, 29, 30 or 31 days, the month day numerals must include as many as 31 month day numerals registered with the aforementioned window and if that month has only 28, 29 or 30 days, the calendar is incorrect at the end of the month indicating at least one extra day in the month causing some persons to be confused by the extra day or a plurality of extra days.
Accordingly, a need exists for a perpetual calendar which may be properly set according to the number of days in a month independent of whether that month includes 28, 29, 30 and 31 days.
Examples of previously known forms of perpetual calendars including some of the structural and operational features of the instant invention are disclosed in U.S. Pat. Nos. 45,064, 201,831, 304,340, 1,692,392 and 2,567,395.